Polysiloxanes terminated with a polymerizable group (e.g., methacrylate, acrylate or vinylcarbonate group) are known from Patent Document 1 (JP-A H08-501504), for example. Patent Document 1 also describes that the polysiloxanes are copolymerized with hydrophilic monomers to form hydrophilic silicone contact lenses or silicone hydrogels. Although polysiloxanes terminated with a urethane bond are fully compatible with hydrophilic monomers such as N-vinylpyrrolidone, those polysiloxanes terminated solely with a polymerizable group are less compatible with hydrophilic monomers and unsuitable as the starting material for silicone hydrogels.
Patent Document 2 (JP-A 2009-542674) discloses a single end glycerol (meth)acrylate-modified silicone resulting from platinum-catalyzed addition reaction of a silicone pentamer having a SiH group at one end with allyl glycerol (meth)acrylate. However, Patent Document 2 refers to neither dual end glycerol (meth)acrylate-modified silicones nor the removal of excess allyl compounds used in the preparation of modified silicones.